1. Field of the Invention
The present invention relates to a device and method for enhancing the light trapping in light harvesting devices. Particularly, the present invention relates to collecting light from a large surface area of the light harvesting device comprising a light absorbing material and trapping the light within the device so as to increase the optical path through the light absorbing material and improve the useful light absorption. More particularly, the present invention relates to enhancing the light trapping in photovoltaic solar panels, light detectors, day lighting systems, bioreactors, water light-treatment reactors, and the like.
2. Description of Background Art
Many light harvesting devices employ a light-absorbing active layer that has at least a partial transparency with respect to the incident light or absorbs more weakly in certain wavelengths than in the others. Conventionally, the absorption in such devices can be improved by increasing the thickness of the active layer. However, this results in the increased system dimensions, material consumption, weight and cost. Alternatively, light trapping approaches are well known in which the light path is altered within the device by micro-texturing one or more device surfaces. While this allows to somewhat increase the light path length and thus improve absorption compared to a non-textured device, a significant portion of the light may still escape from the device without being fully absorbed. It is therefore an object of this invention to provide an improved optical structure that can be used in conjunction with light harvesting devices and that can provide efficient light trapping with minimal energy loss.
The present invention solves the above problems by providing a transparent optical cover structure having one or more micro-structured surfaces that allow for trapping the incident light within the light harvesting device by means of at least TIR and cause the multiple passage of the trapped light through the active layer thus improving the light absorbtion and device efficiency at the minimum consumption of active layer's material. Other objects and advantages of this invention will be apparent to those skilled in the art from the following disclosure.